平均ゲインに着目したPWMインバータの制御方式

抄録

The sinusoidal inverters which convert D.C. voltage source to A.C. voltage source by firing the switching devices with a suitable angles have been widly used in the A.C. machine drive system. To obtain the nearly A.C. output voltage it is necessary to determine the firing angles which produce the output voltage having the following properties, its low-oder harmonics distortion are eliminated and fundamental component is equal to A.C. reference and is insensitive to disturbance of system occuring from the fluctuation of D.C. voltage source or the load harmonics caused by nonlinear loads. There have been many schemes to give the firing angles so far, such as optimal firing angle solved by off-line computation, subharmonics modulation. By these schemes, however, the disturbance of system can not be suppressed.
This paper describes a new PWM control strategy for sinusoidal inverters. This scheme considers the average of gain between the output voltage and the A.C. reference as a criterion for determining the firing angles of the inverter. The theoretical analysis is presented and verified through the simulation. The simulation results show that by this scheme the low-order harmonics distortion are almost eliminated and the fundamental component is also regulated to the A.C. reference. Futhermore the output voltage is insensitive to influence of disturbance occuring from the fluctuation of D.C. voltage source.